That leaves the Rays without a key player for the next few weeks as they battle for the American League East title. But an MRI showed no structual damage, and the team is confident the All-Star will be able to return by Aug. 13, when he's eligible to come off the DL, the Tampa Bay Times reported.

"The goal is to be healthy for the last month and a half," Moore tweeted. "I'm very optimistic."

Moore, 24, is 14-3 with a 3.41 ERA in 21 starts for the Rays this season.